The present invention relates generally to a system, method and computer readable medium of detecting and correctly interpreting repeated touches of one or more users of a touch sensitive screen.
Touch input systems have become ubiquitous throughout industrialized countries. These systems have replaced or supplemented conventional input systems, such as keyboard or mouse in many applications, including for example, information kiosks, retail point of sale, order input (e.g., restaurants), and industrial line operations. Various sensing technologies are applied in touch input systems currently in marketplace, including acoustic, resistive, capacitive and infrared. A touch input system is typically used in conjunction with some type of information display system that may include a computer. When a user touches a displayed object, the touch input system communicates the location of the touch to the system.
Usually one, two or more sensors are used to simultaneously detect signals originated from a touch event. Analysis of such signals allows identifying location and the relative strength of the contact. For example, U.S. Pat. No. 6,922,642 “Contact sensitive device” by D. M. Sullivan describes a contact sensitive device which uses bending wave vibration for extracting information relating to the contact from simultaneous measurements of two or more sensors.
Correctly detecting the false or true touch and location of the touch is very important. Unfortunately this may not be always achieved with desired level of reliability. Various approaches are available in prior art. For example, U.S. Pat. No. 6,492,279 “Dual sensor touch screen utilizing projective-capacitive and force touch sensors” by Joel Kent et al, describes a method and apparatus for discriminating against false touches in a touch screen system, where the system is designed to confirm a touch registered by one touch sensor with another touch sensor, preferably of a different sensor type, prior to acting upon the touch. Another approach is described in U.S. Pat. No. 5,543,589 “Touchpad with dual sensor that simplifies scanning” by William A. Buchana et al. This patent discloses a dual sensor touch screen in which each sensor determines touch and its position, but with a different resolution. While such systems increases touch detection reliability they also increase the cost of the system.
Alternative approaches in prior art systems rely on a single sensor detection where touch pressure is measured and decision is made on whether to act upon a touch or not depending on the measured value. For example, U.S. Pat. No. 5,510,813 “Data processing device comprising a touch screen and a force sensor” by Kofi A. A. Makinwa et al describes a system where the force of the touch is determined. In response to a touch, the system processes the detected force of the touch according to the needs of the application. Some applications available in the market place today rely on such single touch force measurement, and if the touch force/pressure is below certain value, the touch event is discarded. This often leads to unsatisfactory customer experience. Therefore a method and apparatus are needed to improve touch detection while keeping the cost low.